This invention pertains to an adjustable work support which is automatically self-adjusting to a supporting position beneath a workpiece and which may be held firmly in adjusted position under substantial load force of the workpiece.
Adjustable work supports are known in the prior art. Such supports have had an adjustable work-supporting plunger which may automatically move to an adjusted position and which is held in such position by the application of force applied either mechanically or hydraulically. The application of hydraulically applied force includes application to a compressive sleeve surrounding a stem of a work-supporting plunger, as shown in U.S. Pat. No. 3,729,185. Another type of structure is as shown in Tridgell U.S. Pat. No. 3,421,750 wherein a hydraulically-actuated piston applies force to two sets of interleaved flat plates with one set being stationary and the other set having plates alternating with plates of the first set and being movable with the work-supporting plunger. When the plunger moves to a position required for support of a workpiece, the hydraulically operated piston causes compressive engagement between the interleaved plates to hold the plunger in adjusted position.
The use of a wedging action to hold an adjustable work support in position is shown in Cleveland U.S. Pat. No. RE. 23,732.